Abstract. In this paper an object learning system for image understanding is proposed. The knowledge acquisition system is designed as a supervised learning task, which emphasises the role of the user as teacher of the system and allows to obtain the object description as well as to select the best recognition strategy for each specific object. From several representative examples in training images, an object description is acquired by considering different model representations. Moreover, different recognition strategies are built and applied to obtain initial results. Next, teacher evaluates these results and the system automatically selects the specific strategy which best recognise each object. Experimental results are shown and discussed.